It was half past midnight and dismally dark. The distant street lights were just bright enough to illuminate my breath and the tombstones to my left. It was bitterly cold and every so often a very faint breeze would gently move the undergrowth in a disconcerting way.
Why, I began to wonder, was I stood in the dark, in a graveyard next to a disused chapel measuring noise levels? Perhaps unusual jobs just tend naturally to gravitate towards me. No, there were no sharks involved, however, there was a nightclub. Yes! I know it sounds unlikely. Perhaps I should explain by starting at the beginning.
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Photograph 1.
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The chapel has been derelict for many years. It has a listed facade and was once a very attractive building as can be seen in Photograph 1. During its working life many of the chapel's congregation had been buried in graves running down the side of the building (see Photograph 2). The front looks out onto a very busy town centre road whilst at the back is a car park. Buildings have been built on either side of the chapel hard up against the graves.
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Photograph 2. The disused graveyard.
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Photograph 2 shows the chapel to the right with an office building and shop immediately to the left of the graves. This photograph was taken looking towards the road in front of the chapel.
The land had been bought by a developer with the
intention of retaining the listed façade and converting it into
a high quality nightclub. We had designed the nightclub
to adequately contain the music noise and this was not an issue. The
reason the project
had gone as far as a Public Inquiry was the issue
of people and vehicle noise due to patrons leaving the nightclub.
The road in front of the chapel, like most town centre roads, had a lot of traffic on it, both pedestrian and vehicular. The result was a very noisy environment into which the nightclub would add more of the same type of noise. The parameter we used to assess the noise climate was the Leq value since the L10, L90 and Lmax values would be largely unaffected by an increased number of events.
We had predicted the effect of the additional cars and people and had prepared our case comparing these to a measurement of typically 62 dB LAeq at midnight. We were very puzzled to learn that the local authority had been on the site and had measured only about 52 dB LAeq at the same time of night.
Small discrepancies we could have explained as variations in the activities, however, a 10 dB difference was disconcerting to say the least. The local authority had measured the noise levels on the site level with the facade of the chapel. At first this sounded sensible and it wasn't until we caught site of a photograph of where they had measured that the explanation became obvious. They had measured behind the 2.5m high hoarding and were screened from the traffic on the street. Whilst such a screening effect is obvious to most acousticians convincing an inspector required that we get some proof.
So there I was in a graveyard, at midnight, measuring noise levels at two positions. The first above the hoarding at about first floor window height and the second behind the hoarding but level with the facade i.e. exactly where the local authority had measured. Graph 1 shows the actual measured noise levels and Graph 2 the difference between them which was an average of 10.7 dB LAeq
This evidence strengthened our case and the inspector subsequently ruled in our clients favour and granted planning permission. This was a most unusual survey, however, I can report that the only spirits I encountered were in the mini-bar later in my hotel room.
Four weeks later I found myself standing measuring noise levels in another graveyard halfway across the country. This, however, is a story for another time, however, I can tell you that so far graveyards fail the test of quietness!
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